Michael Kenney, an associate professor of international affairs at the University of Pittsburgh Graduate School, says he suspects the coordinated bombings at the Boston Marathon are an act of terrorism.

Explosions killed three people and injured many more on Monday as thousands took part in one of the major running events in the country. Members of the Steel City Road Runners said they finished the race about an hour before the explosions.

"Sirens, EMS and everything you can imagine headed toward the city, and my first thought was we got to get out of Boston as fast as possible," said runner Dave Spell.

Team members said they are glad their group was unharmed, but they are saddened by the loss of life and the heaviness that has fallen over a highly celebrated event.

"Something like this happens, and you can't erase that, and it puts such a dark spin on things," said Aaron Horrell, a member of the Steel City Road Runners.

John Kissell was leaving the Boston Marathon on Monday when he noticed a bunch of people being turned away from the subway.

"We were leaving the area, trying to get on a 'T,' and just then there were all the passengers coming back toward us, and there were several officers right there blocking the entrance to the 'T,' saying, 'Everything's shut down. Explosions just went off at the finish line,'" Kissell told Channel 4 Action News reporter Bob Hazen.

Kissell was about half a mile from the finish line, where he and friends from Steel City Road Runners had crossed about 30 minutes prior.

"It was a little surreal. People didn't really seem to be processing what was going on," said Kissell.

Emily Kobak, a former Moon Township resident turned Bostonian, was about 2-3 miles from the finish line cheering on runners when she heard two loud noises.

It wasn't until she and her boyfriend were waiting to get inside a restaurant when they heard a group mention an explosion and began receiving texts asking if they were OK. Once they were inside, they saw what was happening on TV.

"Where I was, I wouldn't say it was total panic, but there was concern. You could tell that something that happened and people were definitely … you could see the look on their faces, you could tell by conversations. People were concerned," Kobak said.

Once it became clear what had happened, Kissell said it was "really hard to wrap your head around."

He was waiting for a flight back to Pittsburgh on Monday afternoon and was keeping in touch with friends who didn't have cellphone service through Facebook, but said there were still one or two people he was still waiting to hear from.

"They were actually in one of the later corrals where they would have been finishing closer to that time (of the explosions). It's very possible they just were unable to pick up their gear bags that would have had their phones in them. We're just keeping a close watch on that right now," said Kissell.

Kissell told Hazen he didn't notice anything unusual when he crossed the finish line, but that someone clearly had different plans for an event that so many people look forward to.

"We all woke up this morning excited for one of the best races in the world. Apparently a couple people woke up with very different intentions, and that's the thing that's just kind of spooky to think that actually happened," he said.

"It was a beautiful day, beautiful weather," said Kobak. "It just wasn't the way to end such a great day that everybody looks forward to all year round."